Premier League champions City kept their hopes of reaching the Champions League knockout stages alive by beating Bayern Munich 3-2 in Group E on match day five, Aguero taking centre stage with a fine hat-trick.
That set up a final-game showdown with Serie A side Roma with both teams still harbouring hopes of reaching the round of 16.
City's chances were dealt a blow on Saturday, though, as Aguero limped off in the early stages of the 1-0 victory over Everton with suspected knee ligament damage.
While the Argentina international striker's absence could boost Roma's chances, Garcia takes no pleasure in the fact the 26-year-old will not be involved at the Stadio Olimpico.
"You cannot be playing every three days with the same players all the time for many reasons," Garcia said.
"One of them is because a player could pick up an injury as Aguero did and for whom I feel very sorry.
"Great players have to play great games, Aguero is one of the greatest for sure and I'm honestly sorry for him also because I'd love to watch him playing at the Stadio Olimpico.
"City had [Edin] Dzeko out through injury and Aguero played many many games recently and at the end he got injured."
Dzeko returned from injury to feature on the substitutes' bench against Everton, though the Bosnian was not considered fit enough to replace Aguero.
That distinction went to teenage Spaniard Jose Angel Pozo, who may be tasked with starting the crucial clash in the Italian capital if Dzeko is yet to fully recover.
